KR100831081B1 - Adhesive resin for expansion sheet using mutually reactive copolymers and expansion sheet using their adhesive - Google Patents

Abstract

An adhesive resin for a foamed sheet, and a foamed sheet using the adhesive resin are provided to reduce the variation of the characteristics of foamed sheets, thereby improving stability. An adhesive resin for a foamed sheet is prepared by mixing at least two kinds of copolymers having inter-reactivity each other; and a thermally expanding microsphere. Preferably the copolymers having inter-reactivity are a vinyl copolymer having a carboxyl functional group and a vinyl copolymer having an oxazoline functional group; and the thermally expanding microsphere has an average diameter of 10-25 micrometers.

Description

Adhesive resin for expansion sheet using mutually reactive copolymers and expansion sheet using their adhesive}

1 is a cross-sectional view of the foam sheet according to the present invention,

FIG. 2 is a diagram showing a crosslinking mechanism of interreactive polymers in chemical formula. FIG.

* Explanation of symbols on the main parts of the drawings

1: description

2: surface treatment layer

3: foam adhesive layer mixed with mutually reactive copolymers

4: release film

The present invention is an adhesive resin for a foam sheet that is stable for a long time without cross-linking at room temperature using mutually reactive copolymers and a foam sheet that can be easily peeled from the adherend at a high temperature while using excellent adhesive strength (heating Release type adhesive sheet).

The foam sheet adhered to the adherend contains thermally expandable microspheres in order to be easily peeled off from the adherend by heat treatment. When the pressure-sensitive adhesive layer is heated, the thermally expandable microspheres foam and expand to penetrate the pressure-sensitive adhesive layer to reduce the adhesion area with the adherend and peel off.

Conventionally, the adhesive resin used for the foam sheet processed product generally uses an isocyanate crosslinking agent as a copolymer resin of the monomer and acrylic monomer which have a hydroxyl group as a crosslinking functional group. However, in recent years, the foam sheet applied to electronic products is required to be foamed at a high temperature of 150 ℃ or more, the microspheres for foam sheet foamed at a high temperature is limited to use for high temperature since the foam is started at 150 ℃. These limitations can be solved by cohesive or supportive adhesive resins that suppress the expansion of microspheres. Another method can be controlled by chemical design of the vinyl monomer constituting the adhesive resin, but it is not so easy.

Therefore, it is good to change the crosslinking method in consideration of adhesiveness, cohesion, heat resistance, flexibility and elasticity.

Especially in the case of the conventional adhesive resin for foam sheet, a lot of time is required for the complete mixing and dispersion of microspheres in the production of adhesive resin for foam sheet. In this process, the crosslinking agent is gradually crosslinked to increase viscosity. Gelation proceeds and causes a large defect in the coating process. In particular, as the degree of crosslinking is increased to suppress the expansion of the microspheres, more serious problems occur.

In addition, the adhesive resin used in the conventional heat-peelable foam sheet is an acrylic resin containing a crosslinking functional group, and after mixing the crosslinking agent, crosslinking occurs during mixing and dispersion of the microspheres and coating, and thus the viscosity changes and thus the coating is uniform. There is a problem. In particular, this phenomenon is also a problem when the ratio of the cross-linking functional group is large in order to increase the degree of crosslinking.

In order to solve the above disadvantages, the foam sheet obtained by using the adhesive resin obtained in the present invention is detached and attached to the FPCB during the process of the FPCB performed under high temperature conditions or high temperature repeat conditions, grinding of the semiconductor wafer, semiconductor chips, chip capacitors, In the manufacturing process of chip varistors and inductors, it can be used in the fields such as electrode printing, fixing, cutting, detachment and attachment of heat.

In order to improve the above disadvantages, the present applicant can use a mixture of mutually reactive copolymers containing microspheres to sufficiently increase the pot life, and even after mixing for 2 to 3 days, the viscosity changes. The present invention has been completed by finding the fact that there is little.

That is, it was found that by the reaction of two functional groups, that is, a carboxyl group and an oxazoline group, it is possible to impart chemical crosslinking of the amide-ester and to impart physical crosslinking such as hydrogen bonding. It has also been found that because of the high cohesive force, the microspheres require higher temperatures to foam or expand the adhesive layer and have the effect of causing foaming at high temperatures.

Therefore, such a heat-foamable pressure-sensitive adhesive sheet can lower the adhesive strength and easily peel off from the adherend by foaming the microspheres contained in the pressure-sensitive adhesive layer at a temperature higher than the foaming temperature at which the microspheres can expand under normal conditions. When the work is repeated several times at a temperature higher than 150 ° C. or at a high temperature, that is, after cooling in a state of heating at a constant temperature and then cooling and heating again, the foam sheet is continuously foamed at a high temperature since the foaming temperature is continuously lowered. There is a need for a foam sheet, which has been found to provide the pressure-sensitive adhesive of the present invention for this purpose.

In the present invention, the adhesive resin obtained by mixing the mutual reactive copolymers having a carboxyl group and an oxazoline group as a functional group is highly stabilized at room temperature, and is reacted at 100 ° C. or higher to form an ester-amide bond and crosslink, thereby expanding the microspheres. The cohesive force and elasticity of the pressure-sensitive adhesive increases, so that the foaming temperature of the microsphere is higher. Therefore, the initial adhesive strength is excellent and the base and the holding force are excellent. A mold adhesive sheet can be provided.

The present invention having the above effect is a pressure-sensitive adhesive in which two liquids of the first copolymer having an interreactive carboxyl group and the second copolymer having an oxazoline group are mixed, but the crosslinking reaction does not occur at room temperature, and thus the long-term storage at room temperature is excellent. It is possible to facilitate the production of foam sheet having an effective high-density adhesive layer because crosslinking proceeds in the vicinity of 100 ℃.

In addition, the present invention can be foamed at a high temperature of 150 ℃ or more using a pressure-sensitive adhesive obtained by mixing acrylic copolymers each having a carboxyl group and an oxazoline, which are mutually reactive groups, and a coating resin prepared by dispersing microspheres therein. Foam sheet can be prepared.

The present invention relates to an adhesive resin for a foam sheet using a mutual reactive copolymer and a foam sheet using the same, characterized in that the adhesive resin is prepared by mixing interreactive copolymers including thermally expandable microspheres, The pressure-sensitive adhesive resin is coated on one or both sides of the substrate to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is characterized in that a foam sheet (heat-peelable pressure-sensitive adhesive sheet) is produced by foaming or expanding by heating.

Hereinafter, the adhesive resin and the foam sheet using the same according to the present invention will be described in detail.

The adhesive resin according to the present invention is characterized by including thermally expandable microspheres and mutually reactive copolymers.

The thermally expandable microspheres are substances which easily gasify and exhibit thermal expansion like isobutane, propane and pentane, and their shells are thermally soluble as copolymers such as vinylidene chloride, acrylonitrile and methyl methacrylate. It is composed of a material or a thermally expandable material, and depending on the composition and thickness of the shell, it is sold to expand under various temperature conditions of 100 to 170 ° C. However, this temperature is the maximum foaming point temperature, the foaming start temperature is 20 to 50 ℃ lower than this.

Dispersion is advantageous in the adhesive resin that the microspheres have an average particle diameter of 10 to 25 µm, the deformation of the adhesive layer by heat treatment is large, and the drop in adhesive strength is obvious. In addition, it is preferable that the dried foamed adhesive layer is formed of a layer thicker than the maximum particle diameter of the thermally expandable microspheres to smooth the surface of the adhesive layer and achieve stable adhesion before heat treatment.

In order to preferably use the phenomenon of lowering the adhesive strength of the pressure-sensitive adhesive layer by heat treatment, the thermally expandable microspheres are preferably not broken after foaming at a volume expansion rate of 10 times or more. Although the compounding quantity of a thermally expansible microsphere can be suitably determined according to expansion ratio of an adhesion layer, the fall of adhesive force, etc., 5-20 weight part is generally preferable per 100 weight part of adhesive resin which forms an adhesion layer.

On the other hand, the cross-reactive copolymer for dispersing the microsphere is a second copolymer copolymerized with a copolymer of a monomer comprising a vinyl monomer, a comonomer and a carboxyl group and a monomer including a vinyl monomer, a comonomer and an oxazoline group. It is resin which mixed.

The vinyl monomers and vinyl comonomers constituting the first copolymer and the second copolymer are not limited to those which can be appropriately selected and used as necessary, but are used for the purpose of imparting adhesiveness, cohesion, heat resistance, flexibility, etc. of the foam sheet. As such, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acryl Alkyl group-containing vinyl monomers such as acrylate and 2-ethylhexyl acrylate; Hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate Hydroxyl group-containing vinyl monomers such as late; N-substituted amide vinyl monomers such as N, N-dimethyl acrylamide and N, N-dimethyl methacrylamide; Alkoxyalkyl acrylate vinyl monomers such as methoxyethyl acrylate, methoxyethyl methacrylate, ethoxyethyl acrylate, and ethoxy ethyl methacrylate; Vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole Vinyl monomers such as vinylmorpholine, N-vinylcarboxamide, styrene, α-methylstyrene, and N-vinylcaprolactam; Cyanoacrylate vinyl monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl acrylate and glycidyl methacrylate; Polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, methoxy ethylene glycol acrylate, methoxy polyethylene glycol methacrylate, methoxy polypropylene glycol acrylate, methoxy poly Glycol-based acrylic ester monomers such as propylene glycol methacrylate; Acrylic acid ester monomers such as tetrahydroperpril acrylate, tetrahydroperryl methacrylate and 2-methoxyethyl acrylate; Monomers such as isoprene, butadiene, isobutylene and vinyl ether; Or a group consisting of two or more of these mixtures.

The vinyl monomer and comonomer constituting the first copolymer containing the carboxyl group and the second copolymer containing the oxazoline group are preferably introduced in an amount of 80 to 95% by weight of the total adhesive resin. When the vinyl and the comonomer is included in less than 80% by weight, the content of the crosslinking functional group is increased to have a high degree of crosslinking, so that the adhesive force is largely lost and brittleness is generated. In addition, it is difficult to control the polymerization rate or the copolymer composition ratio due to the difference in polarity and reactivity ratio when copolymerizing with a monomer having a large polar functional group. The vinyl comonomer may be used in a mixture of two or more kinds, and may slightly increase the properties of the adhesive resin obtained by controlling the content as a general vinyl comonomer.

The first copolymer containing a carboxyl group is prepared by solution polymerization and for the purpose of imparting crosslinking properties, for example, acrylic acid or methacrylic acid, carboxyethyl acrylate or carboxy pentyl acrylate, itaconic acid or maleic acid, Carboxyl group-containing monomers such as malic acid and crotonic acid; Functional monomers, such as an acid anhydride monomer like maleic anhydride and an itaconic acid anhydride; These are what copolymerized 2 or 3 types or more.

The vinyl monomer containing a carboxyl group as a crosslinking functional group constituting the copolymer is preferably introduced in an amount of 5 to 20% by weight based on the total monomers of the copolymer, preferably in an amount of 5 to 10% by weight. Can be. When the vinyl monomer including the carboxyl group is included in less than 5% by weight, the degree of crosslinking is insufficient, thereby increasing the flexibility of the membrane or decreasing the cohesive force, thereby preventing the expansion of microspheres.

The second copolymer containing an oxazoline group is prepared by solution polymerization and used for the purpose of imparting crosslinkability. Examples of the vinyl monomer containing an oxazoline group include 2-vinyl-2-oxazoline and 2-vinyl-4. -Vinyl-2-oxazoline, 2-vinyl-5-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-iso Propenyl-5-methyl-2-oxazoline, 2- (vinylbenzyloxy-1-methylethyl) -2-oxazoline, 2- (2-hydroxy-1-methylethyl) acrylate, 2- (2 -Hydroxy-1-methylethyl) methacrylate or a group selected from the group consisting of two or more thereof can be used.

The vinyl monomer including the oxazoline group constituting the copolymer is preferably introduced in an amount of 5 to 20% by weight based on the total monomers of the copolymer, and may be introduced in an amount of 10 to 5% by weight. . When the vinyl monomer including the oxazoline group is included in less than 5% by weight, the degree of crosslinking is insufficient, thereby increasing the flexibility of the membrane or decreasing the cohesive force, thereby preventing the expansion of the microspheres.

Adhesive resin for foam sheet using the interreactive copolymer mixture of the present invention synthesizes a first copolymer containing a carboxyl group in the first step, and a second copolymer containing an oxazoline group in the second step In the step is prepared by dispersing the microspheres in the adhesive resin mixed with the first copolymer and the second copolymer. The pressure-sensitive adhesive resin made of such a pressure-sensitive adhesive resin is a stable coating liquid with no change over time even after long-term storage at room temperature and at the same time can increase the foaming temperature to 20 to 30 ℃ or more.

In addition, the foam sheet of the present invention is produced by applying a release film after applying the adhesive resin prepared as described above to one or both sides of the substrate to form an adhesive layer, and has a good adhesion between the substrate and the adhesive layer It characterized in that it further comprises the step of surface treatment. A cross-sectional view of an embodiment of the foam sheet according to the present invention is shown in Figure 1, the substrate 1, the surface treatment layer (2), the foamed adhesive layer (3), the release film (4) mixed with the interreactive copolymers It is composed.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples. However, these examples are only presented to understand the content of the present invention and should not be construed that the scope of the present invention is limited to these embodiments.

[Production Example 1]

First step; Preparation of the First Copolymer

Ethyl acrylate (45 g), comonomer n-butyl acrylate (45 g) and acrylic acid (10 g) are mixed in a 2 L glass reactor equipped with a stirrer, a condenser, a dropping funnel, a thermometer and a jacket. The initiator α, α'-azobisisobutyronitrile (0.01 g) was added to ethyl acetate (100 g) and toluene (20 g), and the radical polymerization reaction was carried out at 70 ° C. After about 30 minutes, ethyl acrylate (135 g), comonomer n-butyl acrylate (135 g), and acrylic acid (30 g) were mixed, and the initiator α, α'-azobisisobutyronitrile (0.5 g) was added thereto. Ethyl acetate (100 g) and toluene (40 g) were added dropwise using a dropping funnel for about 90 minutes. After adjusting the temperature constantly at the time of dropping and dissolving the radical monomer (1 g) in ethyl acetate (50 g) and ethanol (50 g) to prevent unreacted monomer after the reaction was completed, the mixture was added dropwise for 60 minutes and further reacted for 3 hours. The first copolymer was prepared.

Second step; Preparation of Second Copolymer

Ethyl acrylate (45 g) as a monomer, comonomer n-butyl acrylate (45 g) and 2-isopropyl-2-oxa in a 2 L glass reactor equipped with a stirrer, condenser, dropping funnel, thermometer, and jacket Sleepy (10 g) was mixed. An initiator α, α'-azobisisobutyronitrile (0.01 g) was added to ethyl acetate (100 g) and toluene (20 g), and the polymerization was carried out in the same manner as in the polymerization of a copolymer including a carboxyl group at 70 ° C. A radical polymerization reaction was performed. After about 30 minutes, ethyl acrylate (135 g), comonomer n-butyl acrylate (135 g), and acrylic acid (30 g) were mixed, and the initiator α, α'-azobisisobutyronitrile (0.5 g) was added thereto. Ethyl acetate (100 g) and toluene (40 g) were added dropwise using a dropping funnel for about 90 minutes. After adjusting the temperature constantly at the time of dropping, dissolving the radical initiator (1 g) in ethyl acetate (50 g) and ethanol (50 g) so as not to leave unreacted monomer after the reaction was completed, and further reacted for another 3 minutes, and then the second Copolymers were prepared.

Third step; Preparation of Adhesive Resin

The two copolymer resins prepared in the first and second steps were mixed at a weight ratio of 1: 1. A microsphere F-50D (trade name, manufactured by Matsudodo Co., Ltd., 100-105 ° C. foaming start) (10 g) was added to the mixed resin (100 g) and dispersed to prepare an adhesive resin.

[Production Example 2]

A pressure-sensitive adhesive resin was prepared in the same manner as in Preparation Example 1, except that the weight ratio of the monomers used in the first step of Example 1 was used as ethyl acrylate / n-butyl acrylate / acrylic acid = 4.5 / 4.5 / 1.5.

[Production Example 3]

A pressure-sensitive adhesive resin was manufactured in the same manner as in Preparation Example 1, except that the weight ratio of the monomers used in the first step of Example 1 was used as ethyl acrylate / n-butyl acrylate / acrylic acid = 4.5 / 4.5 / 0.6.

[Production Example 4]

Adhesive resin in the same manner as in Preparation Example 1 except that the microsphere F-80GSD (trade name, manufactured by Matsudodo, 110-115 ° C. foaming) was used instead of the microsphere F-50D in the third step of Example 1. Was prepared.

Production Example 5

Adhesive resin in the same manner as in Preparation Example 1, except that Microsphere F-80VSD (trade name, manufactured by Matsudodo, 150-160 ° C. foaming) was used instead of Microsphere F-50D in the third step of Example 1. Was prepared.

[Examples 1-5]

Each of the adhesive resins prepared in Preparation Examples 1 to 5 was coated on a PET film (50 μm), and then a foamed adhesive layer of 37 μm was formed, and a foam sheet was prepared by attaching a release paper of 36 μm. The foam sheet thus prepared was aged for 7 days and used for the final test.

[Comparative Production Example 1]

In a 2 L glass reactor equipped with a stirrer, condenser, dropping funnel, thermometer, and jacket, n-butyl acrylate (48.5 g), ethyl acrylate (48.5 g), acrylic acid (2 g), and hydroxypropyl acrylate ( 1.0 g) and α, α'-azobisisobutyronitrile (0.01 g) is dissolved in ethyl acetate (160 g) and toluene (270 g), placed in a dropping funnel, replaced with nitrogen, and the flow continues. After radical polymerization was carried out at 80 ° C. for 8 hours and an excessive amount of radical initiator was added at the end of the reaction so that unreacted monomers were not left. Then, microsphere F-50D (trade name, manufactured by Matsudodo, 100-105 ° C.) was used. (Starting foaming) (10g) was added and dispersed to prepare an adhesive resin.

[Comparative Production Example 2]

A pressure-sensitive adhesive resin was prepared in the same manner as in Comparative Example 1 except that the amount of hydroxypropyl acrylate (2.0 g) having a crosslinking functional group was increased in Comparative Preparation Example 1.

[Comparative Production Example 3]

Except that the microsphere F-80GSD (trade name, manufactured by Matsudodo, 110-115 ℃ foaming) in Comparative Preparation Example 1 was prepared in the same manner as in Comparative Example 1.

[Comparative Production Example 4]

In Comparative Preparation Example 1 except that the microsphere F-80VSD (trade name, manufactured by Matsudodo, 150 to 160 ℃ foaming) was added to prepare a pressure-sensitive adhesive resin in the same manner as in Comparative Example 1.

[Comparative Examples 1-4]

Adhesion resins prepared by the above 1 to 4, respectively, by adding 2 times the amount of an isocyanate crosslinking agent AK-75 (trade name, Aekyung Chemical) to the hydroxyl group functional groups of the adhesive resin to prepare the adhesive resin, PET film (50 After applying to the (μm), a foamed pressure-sensitive adhesive layer of 37 ㎛ was formed and a release sheet of 36 ㎛ was attached to prepare a foam sheet. The foam sheet thus prepared was aged for 7 days and used for the final test.

Preparation Examples 1 to 5, Comparative Preparation Examples 1 to 4 are summarized in Table 1, and the physical properties of the adhesive resin and foam sheet prepared according to the Preparation Examples, Comparative Preparation Examples and Comparative Examples as follows. Measurements were made using the same test method and the results are reported in Tables 2 and 3.

1. Measurement of viscosity change of adhesive resin

The obtained adhesive resin was prevented from evaporation of the solvent at a constant temperature, placed in a container, and evaluated by measuring the viscosity after time using a Brookfield viscometer (Brookfield, DV-II +).

2. Foaming temperature

Foaming temperature was obtained using Perkin-Elmer DSC 7 and obtained at a rate of 10 ° C./min. Foaming temperature was measured by taking a sample from the film after the cross-linking process was completed by aging the adhesive resin mixed with the microsphere on the PET film. The obtained foam sheet was placed on a temperature-controlled hot plate and a 10 mm-thick stainless plate was equilibrated, and then the foam sheet was sandwiched between the foam sheets, and the foam temperature was measured.

3. Adhesion test

 2 kg of a 20 mm wide and 150 mm long heat-peelable pressure-sensitive adhesive sheet sample obtained in Examples and Comparative Examples on a test plate thoroughly washed with isopropanol was placed on a test piece (SUS 304) having a thickness of 2 mm, a width of 50 mm and a length of 200 mm. Automatic squeezed rubber roller device at 30cm / min squeezed once and bonded and left for 30 minutes at room temperature. 180 degree peel adhesion according to "KSA 1107: 2004" (peel rate 300 mm / min, 23 ℃) Was measured by the measuring method. The average value of the adhesive force measured by three test pieces was calculated | required.

As described above, the pressure-sensitive adhesive resin according to the present invention almost did not occur in the viscosity change, and manufactured a foam sheet that can be foamed at a temperature of about 20 to 30 ℃ higher than when using the same product in the microsphere in the prior art can do.

As described in detail above, the adhesive resin for foam sheet having excellent stability as a pressure-sensitive adhesive solution using a mixture mixture of a first copolymer having a carboxyl functional group and a second copolymer containing oxazoline according to the present invention. Can be prepared.

In addition, in the case of other resin liquids having a high reactivity of the crosslinking agent, it is inconvenient to use them as a two-part type adhesive resin just before use. This is due to the reaction of the functional group of the adhesive resin with the crosslinking agent and gelation as time passes. Proceeds so that application to the substrate is impossible or uniform application is impossible. Therefore, even if the coating is different in thickness, the variation of the properties of the foam sheet produced will appear severely. However, since the reactive copolymer mixture including the carboxyl group and the oxazoline reactor, respectively, does not react at all at room temperature, the adhesive resin using the same has a small variation in the properties of the adhesive resin at room temperature, thereby showing a stable value.

In addition, by using a copolymer crosslinking agent, the crosslinking density of the resins is high, and physical bonds such as hydrogen bonds are generated, and cohesive force and retention force are strong, thereby suppressing the expansion of the microspheres, thereby further increasing the foaming temperature to 20 to 30 ° C.

As described above, the present invention forms a pressure-sensitive resin containing microspheres to increase the foaming temperature of the adhesive resin 20 to 30 ℃ more excellent foamability, excellent adhesion, adhesion, holding force, cohesion, etc. Coating resin can be obtained, which is useful for the production of high-temperature foam sheets applied in the field of electronic and electrical materials.

In addition, the foam sheet produced according to the present invention can also be used for permanently adhering an adherend made of a suitable article or the like, but a preferred use is that after adhering the adherend for a predetermined time and achieving the object, Removal is the preferred use. There are various applications of the above. Examples thereof include assembling or cutting, grinding, or FPCB of two or more articles at high temperature, for example, articles made of a polymer and various electrical and electronic devices made of metal, fiber, or paper. The present invention provides a foamed sheet which can be used for a carrier tape, a temporary fixer, or a surface protecting agent or a masking agent for the purpose of preventing contamination damage of a metal plate, a plastic plate, a glass plate, or the like in a circuit process such as the above.

Claims (11)

Adhesive resin for foam sheet, characterized in that the mixture is produced by mixing two or more copolymers having a mutual reactivity and thermally expandable microspheres. The method of claim 1, The copolymer having mutual reactivity is a vinyl copolymer having a carboxyl functional group and a vinyl copolymer having an oxazoline functional group. The method of claim 2, The vinyl copolymer having a carboxyl group is one or more selected from carboxyl group-containing monomers or acid anhydride monomers selected from acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxy pentyl acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid. A pressure-sensitive adhesive resin for a foam sheet, which is prepared from a monomer having a carboxyl group and selected from the group consisting of two or more thereof. The method of claim 3, wherein Adhesive resin for a foam sheet, characterized in that the monomer is contained in 5 to 20% by weight relative to the total monomers constituting the vinyl copolymer having a carboxyl group. The method of claim 2, Vinyl copolymers containing oxazoline groups include 2-vinyl-2-oxazoline, 2-vinyl-4-vinyl-2-oxazoline, 2-vinyl-5-vinyl-2-oxazoline, 2-isopropenyl- 2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2- (vinylbenzyloxy-1-methylethyl) -2- Prepared from monomers selected from oxazoline, 2- (2-hydroxy-1-methylethyl) acrylate or 2- (2-hydroxy-1-methylethyl) methacrylate, alone or as a mixture of two or more thereof Adhesive resin for foam sheet, characterized in that selected from the group consisting of. The method of claim 5, Adhesive resin for a foam sheet, characterized in that the monomer is contained in 5 to 20% by weight relative to the total monomers constituting the vinyl copolymer having an oxazoline group. The method of claim 2, The vinyl copolymer includes an alkyl group-containing vinyl monomer, a hydroxyl group-containing vinyl monomer, an N-substituted amide-based vinyl monomer, an alkoxyalkyl acrylate, cyanoacrylate, an epoxy group-containing acrylic monomer, a glycol-based acrylic ester, an acrylic acid ester, a vinyl acetate , Vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinyl Monomers which are morpholine, N-vinylcarboxamide, styrene, α-methylstyrene, N-vinylcaprolactam, isoprene, butadiene, isobutylene and vinyl ether; Or adhesive resin for foam sheet, characterized in that selected from the group consisting of two or more of these. The method of claim 7, wherein The alkyl group-containing vinyl monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, Octyl acrylate or 2-ethylhexyl acrylate; The hydroxyl group-containing vinyl monomer is hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acryl Rate or hydroxyhexyl methacrylate; N-substituted amide vinyl monomers are N, N-dimethyl acrylamide or N, N-dimethyl methacrylamide; Alkoxyalkyl acrylate vinyl monomers are methoxyethyl acrylate, methoxyethyl methacrylate, ethoxyethyl acrylate or ethoxyethyl methacrylate; cyanoacrylate is acrylonitrile or methacrylonitrile; The epoxy group-containing acrylic monomer is glycidyl acrylate or glycidyl methacrylate; Glycol-based acrylic ester monomers include polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, methoxy ethylene glycol acrylate, methoxy polyethylene glycol methacrylate, methoxy polypropylene glycol Acrylate or methoxypolypropylene glycol methacrylate; Acrylic acid ester is a tetrahydro perpr acrylate, tetrahydro perryl methacrylate or 2-methoxy ethyl acrylate, the adhesive resin for foam sheet. The method of claim 1, Thermally expansible microsphere adhesive resin for foam sheet, characterized in that the average particle diameter of 10 to 25 ㎛. A foam sheet, which is prepared by applying a pressure-sensitive adhesive resin prepared by any one of claims 1 to 9 on one or both sides of a substrate to form an adhesive layer, and then forming a release film. The method of claim 10, Foam sheet, characterized in that the surface treatment of the substrate before applying the adhesive resin to the substrate.

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